Electrical rectifier



.March 9, 1948. L. K. HEDDING ELECTRICAL RECTIFIER 2 Sheets-Sheet l vFiled July 11, 1945 @SEQ Lw m f2.9' @im His Amm Filed July ll, 1945 2Sheets-Sheet 2 mm mJmT mm, mw

m5@ w www. 2 wrm o my W 1K A .m 1 S J v ma m an w Patented Mar. '9, 1948-Linnie K. `Bedding, Wilkinsburg, Pa., assignor to f The Union Switch &Signal Company, .Swiss lvale, Pa., a corporation of PennsylvaniarApplication July 11, 1945,Seri'ai No. 604,372 `4 Claims. (c1. iis- 366)My invention relates to electrical rectiflers, and particularly toelectrical rectiilers of the so-called dry surface contact type, Such asthe well known copper oxide and selenium rectiflers.

In manufacturing rectifleis of the type described it is common practicetoemploy d-iscs or plates of a standard size. and to connect therequired number of suchdiscs or plates in series and parallel with eachother in a stack to provide the required output voltage and current. In

`order to use the fullarea of the plates to advantage it is'sometimesnecessary to provide cooling vanes for transferring the heat generatedwithin the plates to the surrounding atmosphere. A rectier stackcontaining these parts must, therefore, provide for good heat transferfrom plate to vane, and also permit a free circulation of air throughthe assembly. In cases where both sides of the plates areutilized forrectification, a means must also be provided for collectingcurrent fromeach side. L f

One object of my invention is to provide a novel method and structurefor prefabricating a pair of rectifier elements, a cooling vane,suitable contact members and suitable connectors intoa, unit rectifierwhich is easy to manufacture and which -possesses the desired heatdissipating properties.

Anotherobject of my invention is to .provide a unit rectifier ofsuchconstructionthat a number of such unitrectifiers may readily beassembled into a stack or column on a supporting stud or studs withsuitable spacers and insulating washers with the' positive connectorsfacing 'in either or both directions inthe stack, whereby any desiredoutput voltage and current mayreadily. be obtained.

According to the preferred form of my invention, I clamp two rectifierelements, each of which is provided on each side of the element with acontact surface separated from the base plate of the element by arectifying junction, to the opposite sides of a cooling vane by'means ofa rivet which is insulated from'the elements and the vane, and Iinterpose between the inner contact surface of each element and the vanea contact washer which serves the triple purpose of providing good heattransfer between the elements and the` vane. establishing electricalcontact between the in`ner faces of the elements and the vane, andinsuring that the base metal of the elements does not come into contactwith the vane. I also intrpose between the outer contact surface of theone element and one end of the rivet a-spring -contact member and a.negative connector. and between the outer contact surfaces of the otherelement and the other end of the rivet another spring contact member.The negative connector is adapted to be clamped at its free end againstthe vane and serves to connect the outer contact surfaces of bothrectifier elements to the vane, whereby all four contact `surfaces ofthe elements are electrically connect,

ed to the cooling vane. Thebase plate of each element is provided with aprojecting lug to which a positive connector ispfastened. The free endsof the positive connectors are spaced from the elements, and areprovidedwith a through hole for the reception of amounting stud for supportingin a stackthe resulting rectifier unit formed by the elements, the vaneand the contact members, which through holesalign with a hole in .thevane and in the negative connector. Another through hole is provided ineach cooling vane for the reception of a second mounting stud. The partsare so proportioned that the units can be assembled on the studs into astack with the connectors facing in either'or both directions. in thestack, whereby the desired output voltage and current rating can readilybe obtained.

Other objects and characteristic features of my invention will becomeapparent as the description proceeds.

I shall describe two forms of rectifier units embodying my invention anda `rectifier stackA employing these units, and shall then point out thenovel features thereof in claims.

In the laccompanying drawings, Figs. 1 andA 2 are opposite side viewsshowing oneV form of rectifier unit embodying my invention. Fig. 3 is anenlarged sectional viewtaken substantially on the line III-III of Fig.2. Fig. 4 is a side View showing another type of rectifier element whichmay be employed in the rectiier unit shown in Figs. 1, 2 and. 3 in placeof the elements there illustrated. Fig. 5is a vertical sectional view ofthe element shown in Fig. 4. Figs. 6 and 7 are fragmentaryenlargedsectional views showing modiilcations of the rectifier .unitsillustrated in the preceding views.. Fig. 8 is a side elevational viewwith some of the parts in section showing a, rectif-ier stack employingrectifier units of the type described in the preceding views. Fig. 9 isan end view ofthe stack shown in Fig. 8.

Similar reference characters .refer to similar parts in each of ltheseveral views.

Referring rst to Figs. 1 to 3, inclusive, the rectifier unit here shownis designated as a whole by the reference character R, and comprises tworectifier elements El i andr E2 clamped to the opposite sides of acooling vane I by means of a 3 hollow rivet 2 passing locatedholesprovided in the elements and in the vane; As illustrated, the elementsEI and E2 are of the well-known copper oxide type, and each comprises acopper base plate 3, provided on each side with a layer 4` of copperoxide, the central area of the outer surface of .which is coated 4with ametal 'contact layer or layers 5. As is well understood, elements of thetype described exhibit the characteristic of offering a lower resistanceto current which iiows from the oxide to the copper than to currentwhich tends to flow in the opposite direction through the element.

It should be particularly pointed out that while in the unit asillustrated the elements EI and E2 are of the copper oxide type, insofaras my present invention is concerned, these elements might equallywellbe ,of the selenium type shown in Figs. 4' and 5. Referring to Figs. 4and 5, the element here shown comprises a metal plate 6 provided on bothsides with a layer 1 of selenium the central region of which is coatedwitha contact layer 8 of suitable metal such as a tin cadmium alloy. Itis obvious that both types of elements are similar to the extent thateach element of either type includes a carrier electrode provided oneach side with a contact layer separated from the carrier electrode by arectifying junction, and it should be distinctly understood that insofaras my present invention is con cerned it is immaterial which type ofelement is employed in the rectiiier unit R. v

Each of the rectifier elements EI and E2 is separated from the coolingvane I by a metal contact washer 9 of impressionable conducting materialsuch as lead, and the washers 9, the elements EI and E2 and the coolingvane I are all spaced from the rivet 2 by a metal bushing I and aninsulating bushing II. The contact washers 9 serve the triple purpose ofproviding good heat transfer from the rectifier elements to the vane,establishing good electrical contact between the vane and the innercontact layer of the elements, and insuring that the inner and outeredges of the base plates of the elements where the base metal might beexposed do not come into contact with the vane to thereby short circuitthe unit assembly. If desired, the metal bushing I0 and insulatingbushing II may be omitted, and an insulating bushing II a which isthicker than the insulating bushing II may be substituted therefore asshown in Fig. 6.

The rectifier unit also comprises two spring contact members I2 whichare mounted on the riyet 2 at the outer ends of the bushings I0 and II,and which are each provided with a plurality of radially extendingfingers I3 having curved outer ends which bear against, and makeelectrical contact with, the outer contact layer of the adjacentelement. Also mounted on the one end of the unit outside of the adjacentspring contact member is a connector I4, the free end I4a of which isoffset inwardly to a positionin which it lie: dat against the adjacentside of the cooling vane I. Formed in the end I4a oi the connector I4 isa hole I 4b which aligns with a liole Ia in the cooling vane I for thereception of a mounting stud or bolt, as will be yexplained more fullyhereinafter. `The negative connector I4, the spring contact members I2,and the rivet 2 together. constitute means for connecting the outercontact layers of the elements to the cooling vane, and it will beobvious, therefore, that both the inner and outer contact layers of bothrectier through aligned cent1-any aas'nsaa elements are electricallyconnected to the vane.

The base metal of each element is provided with a laterally projectinglug I5 which in the casev of a copperA oxide rectifier elementconstitutes the positive terminal of the element. and secured in anyconvenient manner as by soldering to this lug of each element is apositive connector I6. In the case of a selenium rectifier element thelug would constitute the negative terminal of the element. In order tofacilitate the assembly of the unit into a stack in the manner to beexplained presently, it is desirable that both positive connectors havetheir free ends disposed on the same side of the unit a predetermineddistance from the cooling vane opposite the hole la in the vane, and tothis end the cooling vane is provided with a hole Ib through which theone connector extends to the opposite side of the vane from that onwhich it is connected to the associated lug I5. A hole Ic is alsoprovided in the cooling vane opposite the other lug to` increase theelectrical clearance between the lug and the plate. Formed in the outerend of each connector is a hole I6a which aligns with the hole Ia in thevane and the hole I4b in the negative connector. The cooling vane isfurther provided with still another hole Id for the reception of amounting stud or bolt as will be made clear presently.

With the unit constructed in the mannerl just described, the unit in andof itself constitutes a half wave rectifier, the negative terminal ofwhich is the cooling vane and the positive terminal of which comprisesthe two positive connectors I8. The unit as a whole is held together bypeening over the ends of the rivet into engagement with the one contactwasher I2 and the negative connector I4, and constitutes a readilyhandled assembly of relatively rigid construction.

Ii desired, the metal rivet 2 and metal bushing I 0 may be combined intoa metal bushing Illa constructed as shown in Fig. 7. Referring to Fig.'7, it will be noted that the bushing IIJa is provided at each end witha portion which is adapted to be bent into engagement with the one metalcontact member and the negative connector in place of the usual rivetange so that the bushing performs the combined function previouslyperformed by the separate rivet and bushing.

Referring now to Figs. 8 and 9, I have here shown a plurality ofrectifier units R each of which may be similar to the rectifier unit Rjust described stacked on two bolts 20 and 2|'. The particular stackillustrated` constitutes a full wave rectier and comprises four legs orsections A. B, C and D, each consisting of two rectifier units inseries. The units of the two legs A and Bare assembled on the bolts 20and 2| with their positive connectors I6 facing toward the left, whilethe units of the two remaining legs or sections are assembled on thebolts with their positive connectors I6 facing in the oppositedirection. The

bolts 20 and 2I pass through the holes Ia and Idv in the vane I withconsiderable clearance, and are insulated from the vane by means ofinsulating tubes 22 and 23 which surround the bolts. Thebolt 20 andassociated tube 22 also pass through the opening I4b in the negativeconnector I4 of each unit and the openings |611 in the positiveconnectors I6 of each unit, and mounted on the tube 22 between adjacentunits are two similar metallic spacers 24 which serve to space thepositive connectors of each unit from the associated vane and from thenegative connector of the next adjacent unit. To prevent the units frombecoming short circuited by the spacer .assassin 2l which is disposedbetween the positivo oonnector ot each unit 'and the vane, o! the same Afurther advantage o! a rectifier unit con-l struction embodying myinvention is that when unit, an insulating washer 2l is mounted on centto the said connector.

Also mounted on the tube 22 are ilve 26, 21, 28, 28 and 80 disposedrespectively at the left-hand end of the leg A, at the junction oi' thelegs A and B, at the Junction of the legs B and C, at the junction ofthe legs C and D, and at the right-hand end oi' the leg D. The twoterminals 21 and 28 constitute the alternating input terminals of therectiiler, while the two terminals 28 and .88 when connected togetherconstitute the positive output terminal of the rectifier, andthe middleterminal 28 constitutes the negative output terminal ofthe rectiiler.

The units are spaced apart on the bolt 2| by means of spacers 3l andinsulating washers 28, one such spacer and insulating washer beinginterposed between the vanes oi' each two adjacent.

units. The lengths of the spacers 2| are such that each of these spacersis equal to the combined lengths of the two spacers 22 which aredisposed between the same two adjacent units, together with the combinedthickness of the negative connector i4 of the one unit and the twopositive connectors of the other unit.v To maintain those units parallelbetween which the terminals 21, 28 and 29are interposed, additionalmetal metal washers 32 are provided on the tube 23 at 'one end of theassociated spacer., Also mounted the bolts 20 and 2|, and interposedbetween eachA nut and the adjacent vparts of the stack are a springWasher 35, a mounting plate 36, an insulating washer 3l provided with ametal insert and such additional metal spacer Washers 38 asl may benecessary to maintain the end plates in the desired parallel spacedrelation with respect to the adjacent rectier units. It will be notedthat the end plates extend from'one bolt to the other and are provi-dedat their upper endsA with outtrned flanges. These end plates serve thedual purpose of increasing the rigidity of the stack and facilitate themounting of the rectiiier unit in a suitable housing or supportingframework.

With the rectifier stack constructed outof units embodying my inventionin the manner just described, it will be apparent that each portion ofthe stack in both directions from the center of the stack constitutes anetwork of series connected units. It will also be apparent that while v-each leg of the rectier as shown includes two units connected in seriesany desired number of units may be included in each leg merely byproviding the required number of spacers and insulating washers.

One advantage of a rectiiier unitconstruction embodying my invention isthat it provides a highly elcient transfer of heat from the rectifierelements to the cooling vane.

Another advantage of a rectifier unit construction embodying myinvention is that this construction makes possible both electrical andmechanical inspection prior toassembling the units into a stack.

Still another advantage of a rectier unit construction embodying myinvention is that low -tube 22 at the side of the vane which is ad,1a`

terminals the units are lassembled into a stack inthemann er describedthe main stack assembly pressure is vnot applied to the rectifierelements. The elementsare thus i'ree to move a limited -extern'. againstthe relatively light pressure applied to them by the spring contactmembers I2. Damage to the elements as the result of accidental pressureto the outer edges of the cooling vanes is thus very materiallyminimized.

Another advantage of a rectifier unit construction embodying` myinvention is that when the units are assembled into a stack in theintended manner, a free circulation of air through the stack assemblyisprovided with an excellent transfer or heat fromthe outer faces of therectifier elements and from the cooling vanes directly to the air.

Although I have herein shown and described only a few forms of rectierunits embodying my invention, it is understood that various changes andmodiiications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention. what I claim is: l

1. A rectifier unit comprising a cooling vane, two rectier elementssecured to opposite sides of said vane, each said element comprising ametal plate provided on each side with a contact layer separated fromthe plate by a rectiiying junction, a contact washer of impressionableconducting material interposed between the inner contact layer of eachelement and said vane, two spring contact members one clamped againstthe outer contact. layer of each element,.means connecting said twocontact members together and to said vane, whereby all four contactlayers of said elements are connected to said vane, and two connectorsone connected to each plate, said unit constituting a single waverectiiler of which said vane constitutes one terminal and said conmentseach provided with a hole which aligns with the hole in said vane andone secured to each side of said vane by a metal member passing throughthe holes in said elements and the hole in said vane, each said elementcomprising a metal plate provided on each side with a contact layerseparated from the plate by a rectifying junction, a contact washer ofimpressionable conducting material interposed between the inner contactlayer of each element and said vane and each provided with a hole whichaligns with the holes in said vane and said elements, two

tendant light weight construction.

spring contact members one clamped against the outer contact layer ofeach element by said metal member, means insulating said vane, saidelements and said contact washers from said metal member, a firstconnector secured to one end of A said member and adapted to contactsaid vane to electrically connect both outer contact layers of saidelement to said vane through the medium of said metal member and saidspring contact members, whereby all four contact layers of said elementare connected to said vane, a second connector secured to the metalplate of the one element, and a third connector secured to the metalplate of the other element.

3. A rectifier unit comprising a cooling vane provided with apluralityof through holes, two rectier elements each provided with athrough rivet passing through the holes in said elements,

and one of the holes in said vane, two contact washers of impressionableconducting material, one interposed between the inner contact layer ofeach element and'said vane and each serving the triple purpose ofproviding good heat transfer from the associated element to said vane,establishing electricalcontact between the inner contact face of theassociated element and said vane, and insuring that the inner and outeredges of the plate of each element will be spaced from the vane farenough to prevent the plate from contacting the vane; two spring contactmembers one mounted on said rivet on each end of the rivet to establishelectrical contact between the rivet and the outer contact layer of eachvane, means insulating said rivet from said vane, the plates of saidelements and said contact washers where said rivet passes therethrough,a rst connector mounted on one end of said rivet and adapted to contactsaid plate opposite another of the holes in said vane and provided witha hole which aligns with said other hole in said vane, two otherconnectors one secured to the plate of each element and each providedwith a hole which aligns with said other hole in said vane, whereby amounting stud can be passed through said other hole in said vane and thehole in each of said connectors, said unit constituting a half waverectifier of which the vane serves as one terminal and said otherconnectors jointly serve as the other terminal.

4. A rectifier unit comprising a cooling vane provided with a pluralityof through holes, two rectiiier elements each provided with a throughhole and each comprising a metal plate provided on each side with acontact layer separated from the plate by a. rectifying junction, saidelements being disposed on opposite sides of said vane and being clampedto said vane'by a hollow metal rivet passing through the holes in saidelements and one of the holes in said vane, two contact washers ofimpressionable conducting material, one interposed between the innercontact layer of each element and said vane and each serving the triplepurpose of providing good heat transfer from the associated element tosaid vane, establishing electrical contact between the inner contactface of the associated element and said vane, and insuring that theinner and outer edges of the plate of each element will be spaced fromthe vane far enough to prevent the plate from contacting the vane; twospring contact members one mounted on said rivet on each end of therivet to establish electrical contact between the rivet and the outercontact layer of each vane, means insulating said rivet from said vane,the plates of said elements and said contact washers where said rivetpasses therethrough, a rst connector mounted on one end of said rivetand adapted to contact said plate opposite another oi the holes in saidvane and provided with a hole which aligns with said other hole in saidvane, two other connectors one secured to the plate oi each elementopposite a, hole in said vane, the one said connectorA being carried tothe side of the vane opposite to the element through a contiguous holein the vane and each said connector being spaced a predetermineddistance from the vane and provided with a through hole which alignswith the hole in the other connector and said other hole in said vane,whereby a mounting stud can be passed through said other hole in saidvane and the hole in each of said connectors, said unit constituting ahalf wave rectifier of which the vane serves as one terminal and saidother connectors jointly serve as the other terminal.

LINNIE K. HEDDING.

REFERENCES CITED The following references are of record in the iile ofthis patent:

Great Britain Nov.'2, 1943

